The present invention relates to a foam filler for forming foam inside a hollow structure and filling the inner space of the hollow structure with foam, and to a hollow structure with such a foam filler.
Pillars in vehicles have inner panels and outer panels, for example, which are formed integrally, and thus, have hollow structures. The inner space of these hollow structures is filled with a foam, and thus, vibration in the hollow structure is suppressed, and noise caused by such vibrations are dampened. In addition, the air in the inner space of the hollow structures can be prevented from circulating because of the foam filling the inner space, and noises caused by such circulation of the air are dampened. Thus, noises caused in the hollow structure in vehicles, for example, are dampened, and as a result, the inside of the vehicle is quieter. Conventional foam fillers having a base for forming foam through heating are used to fill the inner space of hollow structures with foam. Such foam fillers are placed inside the hollow structure and heated together with the hollow structure, and thus, the inner space of the hollow structure is filled with the foam.
In general, panels which form a hollow structure have through holes, which are used, for example, for conveyance of the hollow structure, assembly of the hollow structure, and positioning of a number of panels. Such through holes usually become unnecessary after having served these functions. That is to say, there is a risk that the through holes may become holes through which air flows into the hollow structure after use, and become a factor in the creation of noise, for example. Therefore, it is preferable for the through holes after use to be covered with foam as that described above. Furthermore, portions where through holes are created are filled with foam, and thus, vibration of the hollow structure is preferably suppressed. However, when portions where through holes are created are filled with foam, the formed foam may swell out from the hollow structure through the through holes. Portions of the foam that swell out from the hollow structure in this manner are unnecessary. Furthermore, foam that swells out a great deal causes problems after filling in that the foam that fills the inner space prevents interior parts from being attached along the hollow structure. If the foam that swells out is visible, the foam degrades ornamentality. Japanese Laid-Open Patent Publication No. 2001-153231 discloses a foam filler which prevents foam from swelling out from through holes when formed. This foam filler is formed of a base which foams through heating and a net provided on the surface which is joined to a structure. The net has a mesh which is smaller than the through holes provided in the structure, and is arranged on the base so as to coat the through holes in the structure. In this foam filler, the net for covering the through holes prevents the foam from entering the through holes when the base is foamed through heating.
Some of the through holes created in the hollow structure are not used at all after a foam filler is provided inside the hollow structure, and other through holes are used after provision of a foam filler. In the above described conventional foam filler, the base is provided with a net covering the through holes, and therefore, the through holes are clogged with the foam filler in a state where the foam filler is provided in the hollow structure. Accordingly, the through holes are prevented from being used by the provided foam filler after provision of the foam filler in the hollow structure. During the process in which, for example, a hollow structure is attached to a vehicle after provision of a foam filler, through holes which allow an industrial robot arm to grasp the hollow structure are prevented from being used by the foam filler. In addition, during electrodeposition coating of a vehicle body, for example, the foam filler prevents liquid for electrodeposition that has entered the hollow structure from being efficiently discharged through the through holes. That is to say, there is a problem with conventional foam fillers in that through holes are prevented from being used after provision of a foam filler, though the foam is prevented from swelling out through the through holes when portions where through holes are created are efficiently filled with the foam.